Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true, openWorldHint=false, and destructiveHint=false, so safety is covered. The description adds useful behavioral context by mentioning pagination fields, totalCount, and how returned ids feed into update-invoice-draft, which goes beyond the annotation set.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two compact sentences, front-loaded with the list operation and followed by workflow guidance. There is no redundant or filler language.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a read-only list tool with full schema coverage and safety annotations, this gives enough context: what is listed, that results page, and how to use the returned id downstream. No output schema exists, so return-value details are not required, and the description still covers key pagination response fields.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so page, perPage, search, and companyId are already documented in the schema. The description mentions paging but adds no syntax or meaning beyond the schema, making the baseline 3 appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource, 'List a company's invoice customers', and scopes it to invoice customers of a given company. It also names the sibling tools update-invoice-draft and create-customer, helping distinguish this lookup from create/update actions.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly tells the agent to use a returned customer id as customerId in update-invoice-draft and to use create-customer when the customer does not exist yet. This gives clear downstream usage and an alternative for the missing-customer case, though it does not spell out when not to call this list tool.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.